Electronic structure and disorder in Na_xCoO₂ and SrRh₂O₄

Journal Article · Mon Jan 01 00:00:00 EST 2007 · Solid State Sciences

DOI:https://doi.org/10.1016/j.solidstatesciences.2007.03.008· OSTI ID:968234

Singh, David J ^[1]; Kasinathan, Deepa ^[1]; Fornari, M. ^[2]

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1. ORNL
2. Central Michigan University, Mt. Pleasant

We discuss the electronic structure of NaxCoO2 from the point of view of first principles electronic structure calculations. The band structure contains low spin Co ions, with average charge 5+x leading to a nearly full Co t2g manifold. The bands corresponding to this manifold are narrow and separated from the O 2p bands and from the eg bands, which are also narrow. There are two main sheets of Fermi surface, a large section derived from ag symmetry states, and small hole pockets. We find significant effects due to Na disorder on these small sections, with the result that they should be localized. This is discussed in relation to recent photoemission experiments. For comparison, we present a virtual crystal band structure of beta-SrRh2O4. Like NaxCoO2 it shows a large crystal field gap between narrow t2g and eg manifolds, but because of its stoichiometry is a semiconductor rather than a high carrier density metal.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 968234
• Journal Information: Solid State Sciences, Vol. 9; ISSN 1293-2558
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SODIUM OXIDES
COBALT OXIDES
STRONTIUM OXIDES
RHODIUM OXIDES
ELECTRONIC STRUCTURE
FERMI LEVEL
ORDER PARAMETERS